nbody_CPU*: clean up code a bit

Adding some 'const's and fixing some whitespace.

Signed-off-by: Steven Noonan <steven@uplinklabs.net>
nbody_CPU_SOA: eliminate impossible 'if' clause

Given that the condition for the loop is 'j < i', it's not possible to have
a case where 'j == i'.

Signed-off-by: Steven Noonan <steven@uplinklabs.net>
nbody: use size_t for nTile in templates

This makes its type identical to the types of the iterator variables.

Signed-off-by: Steven Noonan <steven@uplinklabs.net>
chLib: make line endings consistent

Standardizing on UNIX (\n) line endings, as that's what the rest of the sources
use.

Signed-off-by: Steven Noonan <steven@uplinklabs.net>
nbody: use -ffast-math on all target platforms

This is particularly critical for the rsqrtf() function:

    snoonan@dispater ~
    $ cat test.c
    #include <math.h>
    float rsqrtf(float x)
    {
	    return 1.0f / sqrtf(x);
    }

    $ gcc --version
    gcc (GCC) 4.8.1 20130725 (prerelease)

Without -ffast-math:

    snoonan@dispater ~
    $ gcc -O3 -S test.c; cat test.s | grep -v -E '\s+?[.][^L]'
    rsqrtf:
    .LFB3:
	    sqrtss	%xmm0, %xmm1
	    ucomiss	%xmm1, %xmm1
	    jp	.L7
	    movss	.LC0(%rip), %xmm0
	    divss	%xmm1, %xmm0
	    ret
    .L7:
	    pushq	%rax
	    call	sqrtf
	    movaps	%xmm0, %xmm1
	    movss	.LC0(%rip), %xmm0
	    divss	%xmm1, %xmm0
	    popq	%rdx
	    ret
    .LFE3:
    .LC0:

With -ffast-math:

    snoonan@dispater ~
    $ gcc -O3 -ffast-math -S test.c; cat test.s | grep -v -E '\s+?[.][^L]'
    rsqrtf:
    .LFB12:
	    rsqrtss	%xmm0, %xmm1
	    mulss	%xmm1, %xmm0
	    mulss	%xmm1, %xmm0
	    mulss	.LC1(%rip), %xmm1
	    addss	.LC0(%rip), %xmm0
	    mulss	%xmm1, %xmm0
	    ret
    .LFE12:
    .LC0:
    .LC1:

Note that it doesn't use 'rsqrtss' without -ffast-math.

Signed-off-by: Steven Noonan <steven@uplinklabs.net>
nbody: make CPU_AOS OpenMP-parallelized

This one's really straightforward since there's no chance of threads stomping
on each other.

Signed-off-by: Steven Noonan <steven@uplinklabs.net>